“There’s much to investigate here. It's amazing to me that an individual like this who was sending out so many signals could end up getting on a plane going to the US,” said Senate Republican leader Mitch McConnell.

Secretary Napolitano backed off her original statements Monday. What worked was the department’s response to the incident, she explained. Within 90 minutes, all 128 planes already in the air from Europe were notified to take appropriate action. There was no panic.

"No secretary of homeland security would sit here and say that a system worked prior to this incident which allowed this individual to get on this plane," the secretary told Fox News on Monday.

Red flags

Looking back, analysts say there were many aspects of Umar Farouk Abdulmutallab, the Nigerian charged with trying to blow up the plane, that could have raised red flags. He had no checked luggage, and he paid for his ticket with cash. Mr. Abdulmutallab’s name had already surfaced on the National Counterterrorism Center’s database of known or suspected international terrorists, but that information was never made it to US airlines.

“Eight years after the 9/11 attacks, this is someone who makes it on one list only to disappear into a bureaucratic black hole,” says Bruce Hoffman, a professor at the Security Studies Program at Georgetown University in Washington. "Eight years after the 9/11 attacks, it’s a compound failure in intelligence and physical security. Once again, valiant and alert passengers are the last line of defense.”

The incident, which ended when passengers tackled the suspect and put out the flames of his failed bomb, is refocusing attention on Capitol Hill. The question is whether the post-9/11 reforms, including the creation of a Department of Homeland Security and Director of National Intelligence, are working as Congress intended.

“Surprise, when it happens to a government, is likely to be a complicated, diffuse, bureaucratic thing. It includes neglect of responsibility, but also responsibility so poorly defined or so ambiguously delegated that action gets lost,” the commission concluded, citing a study on the 1941 surprise attack on Pearl Harbor. “We hope another commission, writing in the future about another attack, does not again find this quotation to be so apt.”

The 9/11 commission recommendations, largely adopted by Congress in 2004, called for creating layers of security, including expanded use of no-fly and “automatic selectee” lists, as well as improved screening checkpoints to detect explosives on passengers.

The Senate Homeland Security and Governmental Affairs Committee is ramping up for hearings on the incident. “It raises some serious questions, such as how was this person able to bring an explosive substance aboard a commercial airliner” said Sen. Susan Collins of Maine, the top Republican on the committee, in a statement.